안녕하세요, 다음은 unix ptx 유틸리티에서 가져온 코드 스 니펫입니다. 이 유틸리티에서 코드 적용 범위를 최대화하려고 시도하고 있지만 표시된 부분에 도달 할 수 없습니다. 물론 필자는 이전처럼 C 스킬이 강하지 않다. 코드 부분은 주석으로 표시되어 있지만 블록의 맨 아래를 향하고 있습니다.코드 적용 범위를 극대화하려면 어떻게해야합니까?
if (used_length == allocated_length)
{
allocated_length += (1 << SWALLOW_REALLOC_LOG);
block->start
= (char *) xrealloc (block->start, allocated_length);
}
해당 블록을 처리하기 위해 표시된 부분을 해석하면 도움이됩니다.
/* Reallocation step when swallowing non regular files. The value is not
the actual reallocation step, but its base two logarithm. */
#define SWALLOW_REALLOC_LOG 12
static void swallow_file_in_memory (const char *file_name, BLOCK *block)
{
int file_handle; /* file descriptor number */
struct stat stat_block; /* stat block for file */
size_t allocated_length; /* allocated length of memory buffer */
size_t used_length; /* used length in memory buffer */
int read_length; /* number of character gotten on last read */
/* As special cases, a file name which is NULL or "-" indicates standard
input, which is already opened. In all other cases, open the file from
its name. */
bool using_stdin = !file_name || !*file_name || strcmp (file_name, "-") == 0;
if (using_stdin)
file_handle = STDIN_FILENO;
else
if ((file_handle = open (file_name, O_RDONLY)) < 0)
error (EXIT_FAILURE, errno, "%s", file_name);
/* If the file is a plain, regular file, allocate the memory buffer all at
once and swallow the file in one blow. In other cases, read the file
repeatedly in smaller chunks until we have it all, reallocating memory
once in a while, as we go. */
if (fstat (file_handle, &stat_block) < 0)
error (EXIT_FAILURE, errno, "%s", file_name);
if (S_ISREG (stat_block.st_mode))
{
size_t in_memory_size;
block->start = (char *) xmalloc ((size_t) stat_block.st_size);
if ((in_memory_size = read (file_handle,
block->start, (size_t) stat_block.st_size))
!= stat_block.st_size)
{
error (EXIT_FAILURE, errno, "%s", file_name);
}
block->end = block->start + in_memory_size;
}
else
{
block->start = (char *) xmalloc ((size_t) 1 << SWALLOW_REALLOC_LOG);
used_length = 0;
allocated_length = (1 << SWALLOW_REALLOC_LOG);
while (read_length = read (file_handle,
block->start + used_length,
allocated_length - used_length),
read_length > 0)
{
used_length += read_length;
/* Cannot cover from this point...*/
if (used_length == allocated_length)
{
allocated_length += (1 << SWALLOW_REALLOC_LOG);
block->start
= (char *) xrealloc (block->start, allocated_length);
}
/* ...to this point. */
}
if (read_length < 0)
error (EXIT_FAILURE, errno, "%s", file_name);
block->end = block->start + used_length;
}
/* Close the file, but only if it was not the standard input. */
if (! using_stdin && close (file_handle) != 0)
error (EXIT_FAILURE, errno, "%s", file_name);
}
고맙습니다. 그것이 문제였습니다. 감사합니다. – naivedeveloper